books.google.ch - Covert channels are unexpected and hidden communication paths embedded within a communication system that violate the system security policy. Covert communication occurs when a user or application deliberately manipulates and embeds in formation into some property of a communication system in such a...https://books.google.ch/books/about/Covert_Channels_in_Secure_Wireless_Netwo.html?hl=de&id=minauAAACAAJ&utm_source=gb-gplus-shareCovert Channels in Secure Wireless Networks